1. Field of the Invention
The present invention relates to a connecting structure of a coil in an electromagnetic relay.
2. Description of the Prior Art
As an example of a coil connecting structure in a conventional electromagnetic relay, there has been known a structure as shown in FIGS. 5 and 6.
That is, a coil core wire 1 is wound around the outer periphery of a bobbin 2 to which a pair of flanges 3 are attached on both sides of the bobbin so as to face each other. A pair of pockets 5 consisting of enclosing grooves which are notched from both side portions of the flange 3 are formed in one of the flanges 3.
Coil lead wires 1a and 1b each of which is formed by extracting the coil core wire 1 or by twisting a plurality of coil core wires 1 and extracting the twisted wire are inserted into the pockets 5. The coil lead wire 1a on the starting side is inserted into one of the pockets 5 from the upper direction and its end portion is wound around the upper surface of a coil terminal 7a implanted onto a terminal base 6 and is soldered to the terminal 7a (refer to FIGS. 7 and 8).
The coil lead wire 1b on the terminating side is inserted into the other pocket 5 and its end portion is wound around the upper surface of another coil terminal 7b implanted onto the terminal base 6 and is soldered in a manner similar to the coil lead wire 1a on the starting side (refer to FIG. 7).
The insulation between the starting side 1a and the terminating side 1b of the coil lead wire 1 is accomplished by a barrier portion 4 formed on the upper surfaces of the pockets 5.
In the above coil connecting structure, the coil core wire 1 is connected with the coil terminals 7a and 7b by using the coil lead wires 1a and 1b each of which is an end portion of the coil core wire 1 or formed by twisting a plurality of coil core wire end portions. Therefore, there is a problem such that when a repetitive bending force due to the tension or vibration is applied to the coil lead wires 1a and 1b, they can be easily fatigued and cut out by the concentration of the stresses.
On the other hand, even in the case where the coil lead wires 1a and 1b are come into contact with the corner portions of the pockets 5 and the tension is applied to them, the coil lead wires 1a and 1b can be easily cut out by the pointed corner portions.
Moreover, since the coil lead wires 1a and 1b have the flexibility, there is also a problem such that the twisted core wires are projected and the good insulating property is not held.
Further, assuming that the end portions of such coil lead wires 1a and 1b were melted and bonded to the coil terminals 7a and 7b, the cross sections of the coil lead wires 1a and 1b decrease due to the dissolution and their strengths are weakened. Therefore, it is improper to connect the coil lead wires by the melt bonding method. Consequently, hitherto, the coil lead wires 1a and 1b are generally connected with the coil terminals 7a and 7b by soldering.
In the case of connecting the coil lead wires 1a and 1b with the coil terminals 7a and 7b by soldering, there are problems such that the flux produced upon soldering is diffused and deposited onto contacts (not shown) of the electromagnetic relay, so that a defective contact is caused and the like.